Novel Technique For Grid Generation Based On Finite Difference Time Domain Method

As a numerical method of electromagnetic field computation, finite-difference time-domain method is simple, direct and easy to master and widely used. It has been used in many aspects of engineering computation of electromagnetic field. Along with the exaltation of the computer function,the usage of FDTD is more wide. The first step of FDTD is geometric modeling. Grid generation is the most important and complex segment of geometric modeling. The efficiency of geometric modeling is determined by the complexity of grid generation. For the engineering application of orthogonal grid generation in finite-difference time-domain (FDTD), there are some problems such as grid miscarriage of justice and being inefficient to generate grids and so on. The purpose of conformal FDTD technique is to reduce the error caused by ladder approximation and it is difficult to generate conformal grid. As to orthogonal grid generation and conformal grid generation, the main work of this paper:1.At first, the most commonly used orthogonal FDTD mesh generation method which called odd-even counting grid generation is introduced. The reason of singularity of grid generation is analysed. Otherwise, we get the theoretical basis of being inefficient to generate grids after analysis of complexity of computation.2.Polar angle determination orthogonal grid generation method which based on computational geometry theory is proposed. Two-dimensional and three-dimensional grid generation process are given in this paper. Compared with odd-even counting grid generation method, we find that polar angle determination orthogonal grid generation algorithm is more efficien and it had no singularity problems. Finally, we validate it by the simulation.3.Piecewise linear interpolation and Hermit interpolation method are used to generate conformal grid of complex objects. It does not only show the conformal mesh generation method but also gives the area element solution formula when the conformal FDTD technique is used to solve electromagnetic field problems. Error of the ladder approximation, piecewise linear interpolation and Hermit interpolation are analysed and compared.